The first question was quite difficult but the rest easy surprised us all.A. was; which

问题补充：

The first question was quite difficult but the rest easy, surprised us all.

A. was; which

B. was; that

C. were; which

D. were; which

答案：

A. was; which

B. was; that

(答案→)C. were; which

D. were; which

解析：考查主谓一致和非限制性定语从句：句意：第一个问题很难，但其余的很简单，这让我们很惊讶。第一空填were，因为the rest做主语时，谓语和the rest修饰的名词决定，这句话修饰的是questions，所以谓语是复数，第二空是非限制性定语从句，用which引导，不能用that引导。选C。